This study is for patients with advanced or stage II and III colon or rectal cancer. The primary purpose of this research study is to determine if a particular protein in the patient's blood will change when they receive treatment with a drug called oxaliplatin, which is used to treat the colon or rectal cancer. This protein is called ERCC-1. It is thought that the amount of this protein in the blood could influence the manner in which the patient responds to oxaliplatin.